Due to the huge size of raw digital video data or image sequences, compression may be applied to such data so that they may be transmitted and stored. Hybrid video coding scheme is the most common video coding scheme. It utilizes motion estimation (ME), discrete cosine transform (DCT)-based transform, and entropy coding to exploit temporal, spatial, and data redundancies, respectively. Most of the existing video coding standards conform to this hybrid scheme, such as ISO/IEC MPEG-1, MPEG-2, and MPEG-4 standards, and ITU-T H.261, H.263, and H.264 standards. ISO/IEC MPEG-1 and MPEG-2 standards are used extensively by the entertainment industry to distribute movies, in the form of applications such as video compact disks (VCDs) (MPEG-1), digital video or digital versatile disks (DVDs) (MPEG-2), recordable DVDs (MPEG-2), digital video broadcast (DVB) (MPEG-2), video-on-demands (VODs) (MPEG-2), high definition television (HDTV) in the US (MPEG-2), etc. MPEG-4 is more advanced than MPEG-2 and can achieve high quality video at lower bit rate, making it suitable for video streaming over internet, digital wireless network (e.g. 3G network), multimedia messaging service (MMS standard from 3GPP), etc. MPEG-4 is accepted for the next generation high definition DVD (HD-DVD) standard and the MMS standard. ITU-T H.261, H.263, and H.264 standards are designed mainly for low-delay video phones and video conferencing systems. The earlier H.261 standard was designed to operate at bit rates of p*64 kbit/s, with p=1, 2, . . . , 31. The later H.263 standard is successful and widely used in modern video conferencing systems, and video streaming in broadband and wireless networks, including the multimedia messaging service (MMS) in 2.5G and 3G networks and beyond. The latest H.264 (also called MPEG-4 Ver. 10 or MPEG-4 AVC) is currently the state-of-the-art video compression standard. It is so powerful that the Moving Picture Experts Group (MPEG) decided to jointly develop the standard with the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T) in the framework of the Joint Video Team (JVT). The new standard is called H.264 in ITU-T and is called MPEG-4 Advance Video Coding (MPEG-4 AVC) or MPEG-4 Version 10 in ISO/IEC. H.264 is used in the HD-DVD standard, Direct Video Broadcast (DVB) standard, MMS standard, etc. Based on H.264,.a related standard called the Audio Visual Standard (AVS) is currently under development in China. AVS 1.0 is designed for high definition television (HDTV). AVS-M is designed for mobile applications. Other related standards may be under development as well.
H.264 has superior objective and subjective video quality over MPEG-1, MPEG-2, and MPEG-4, and H.261 and H.263. The basic encoding algorithm of H.264 (Joint Video Team of ITU-T and ISO/IEC JTC 1, “Draft ITU-T Recommendation and Final Draft International Standard of Joint Video Specification (ITU-T Rec. H.264 | ISO/IEC 14496-10 AVC),” document JVT-G050r1, May 2003) is similar to H.263 or MPEG-4 except that integer 4×4 DCT is used instead of the traditional 8×8 DCT. There are additional features of the H.264 standard including intra-prediction mode for l-frames, multiple block sizes and multiple reference frames for motion estimation/compensation, quarter pixel accuracy for motion estimation, in-loop deblocking filter, context adaptive binary arithmetic coding, etc.
The above-mentioned traditional block-based motion compensated video encoders, e.g. H.263, H.264, are specially designed for the compression of clean video sequences. However, when the input video sequences are corrupted by noise, these encoders may have some problems, e.g. they may generate bitstreams with high bitrate but poor peak signal-to-noise ratio (PSNR) performance. Moreover, the visual quality of output reconstructed video sequences may be noisy. There is a need to address the rate control and denoising problems for the video sequences partially or fully corrupted by Gaussian noise as shown in FIGS. 1(a) and 1(b). In this work, a simultaneously rate controlling and video denoising approach using rate distortion optimization is proposed.